Automotive air conditioning evaporators are known to emit whistling sounds briefly during the startup phase of operation. These sounds have led to customer complaints. Work at the University of Illinois shows that this problem develops when single phase vapor refrigerant flows through the evaporator plate at high velocity. It was further discovered that nitrogen could be used to simulate the phenomenon leading to simpler experimental methods. This paper discusses the development of a technique to use inexpensive rapid prototyping as a tool in the design of new plate evaporators. Some preliminary results along with some limitations of the new technique are discussed.